1. Field of the Invention
This invention relates generally to devices for interventional therapeutic treatment or vascular surgery for treatment of defects in the vasculature, and more particularly concerns a system and method for detaching occlusion balloons for treatment of aneurysms.
2. Description of Related Art
Vasoocclusive devices are typically placed within the vasculature of the human body by use of a catheter, either to block the flow of blood through a vessel making up that portion of the vasculature through the formation of an embolus or to form such an embolus within an aneurysm stemming from the vessel. Vasoocclusive devices used for these procedures can have a variety of configurations, and are generally formed of one or more elements that are larger in the deployed configuration than when they are within the delivery catheter prior to placement. One anatomically shaped vasoocclusive device that forms itself into a shape of an anatomical cavity such as an aneurysm is made of a preformed strand of flexible material such as a nickel-titanium alloy. One or more of such vasoocclusive members can be wound to form a generally spherical or ovoid shape in a relaxed, expanded state.
Aneurysms have been treated with external surgically placed clips, or using vascular catheters, by detachable vasoocclusive balloons or an embolus generating vasoocclusive device such as one or more vasoocclusive coils. The delivery of such vasoocclusive devices can be accomplished by a variety of means, including via a catheter in which the device is pushed through an opening at the distal end of the catheter by a pusher to deploy the device. The vasoocclusive devices can be produced in such a way that they will pass through the lumen of a catheter in a linear shape and take on a complex shape as originally formed after being deployed into the area of interest, such as an aneurysm.
Some conventional vasoocclusive devices are operated by pulling or jerking the catheter tip from the balloon, thus potentially compromising the position of the implant. One such device provides for an endovascular wire and tip that can be separated from the holding wire mechanically or electrolytically for the formation of thrombus in blood vessels. However, such devices that release the interventional device by mechanically breaking an intermediate section between the catheter tip and balloon can potentially leave broken or jagged ends that can potentially injure the vasculature.
One conventional releasable balloon catheter used to embolize vascular lesions has a tube portion made of a material such as a hydrophilic polymer, located between the catheter and the balloon, that can be broken by torsion of the tube. The tube can be melted by heating the tube, or can be dissolved in the blood when heated, and electrodes are provided for heating the tube. Another conventional technique for separating a balloon from a balloon catheter involves the melting and breaking of a connecting member made from polyvinyl alcohol or trans-polyisoprene between the balloon and the catheter body, when power is supplied to electrodes provided for heating the connecting member. When the connecting member is heated to temperatures of about 70.degree. C. and slight tension is applied, the balloon can be separated from the main catheter body. However, such devices that release the interventional device by melting or dissolving the intermediate section between the catheter tip and balloon can also potentially release undesirable particles of materials into the bloodstream.
There is therefore a need for a precise method of detaching occlusion balloons or other therapeutic interventional devices without compromising the position of the implant, without presenting broken or jagged ends that can potentially injure the vasculature, and without releasing undesirable particles of materials into the bloodstream. It is therefore desirable to provide a method and system for cleanly releasing occlusion balloons from a placement catheter for treatment of aneurysms. The present invention meets these needs.